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>Chapter 27. Monitoring Database Activity</H1
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><B
>Table of Contents</B
></DT
><DT
>27.1. <A
HREF="monitoring-ps.html"
>Standard Unix Tools</A
></DT
><DT
>27.2. <A
HREF="monitoring-stats.html"
>The Statistics Collector</A
></DT
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>27.2.1. <A
HREF="monitoring-stats.html#MONITORING-STATS-SETUP"
>Statistics Collection Configuration</A
></DT
><DT
>27.2.2. <A
HREF="monitoring-stats.html#MONITORING-STATS-VIEWS"
>Viewing Collected Statistics</A
></DT
></DL
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>27.3. <A
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>Viewing Locks</A
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>27.4. <A
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>Dynamic Tracing</A
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>27.4.1. <A
HREF="dynamic-trace.html#COMPILING-FOR-TRACE"
>Compiling for Dynamic Tracing</A
></DT
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>27.4.2. <A
HREF="dynamic-trace.html#TRACE-POINTS"
>Built-in Probes</A
></DT
><DT
>27.4.3. <A
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>Using Probes</A
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>27.4.4. <A
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>Defining New Probes</A
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><P
>  A database administrator frequently wonders, <SPAN
CLASS="QUOTE"
>"What is the system
  doing right now?"</SPAN
>
  This chapter discusses how to find that out.
 </P
><P
>   Several tools are available for monitoring database activity and
   analyzing performance.  Most of this chapter is devoted to describing
   <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>'s statistics collector,
   but one should not neglect regular Unix monitoring programs such as
   <TT
CLASS="COMMAND"
>ps</TT
>, <TT
CLASS="COMMAND"
>top</TT
>, <TT
CLASS="COMMAND"
>iostat</TT
>, and <TT
CLASS="COMMAND"
>vmstat</TT
>.
   Also, once one has identified a
   poorly-performing query, further investigation might be needed using
   <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>'s <A
HREF="sql-explain.html"
>EXPLAIN</A
> command.
   <A
HREF="using-explain.html"
>Section 14.1</A
> discusses <TT
CLASS="COMMAND"
>EXPLAIN</TT
>
   and other methods for understanding the behavior of an individual
   query.
  </P
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